Electrical power and communication, ie. utility lines are typically carried by a series of poles which must remain erect for transmission. A substantially uniform tension through each line effects a lateral force upon each such pole determined by the product of this tension and the sine of the angle subtended by the alignments of the line to both poles adjacent a given pole. In line transmission utilizing poles appropriate guying of each pole to counter this lateral force is a necessity to maintain the erect posture of the poles. Economic utilization of guying cable and tackle demands an accurate calculation of this lateral force which relies upon an accurate measure of this subtended angle.
Determining this subtended angle is typically accomplished by one of two methods: 1) use of a transit or theodolite; 2) triangulation with two equal legs measured with tape on the ground. The first method is generally avoided in terrain which is traversed by foot because of the weight and awkwardness of the equipment. The second method suffers from at least three drawbacks: a) two people are generally required; b) leg measurement is tedious; c) accuracy is adversely affected by changes in terrain elevation. It is thus seen that rough or sloped terrain poses a problem to either method practiced currently where utility lines carded by wood poles are a commonplace in rural areas and rough terrain including trees and brush which renders leg measurement particularly difficult is frequently traversed by such lines.